Initially, they almost looked exactly alike, but it wasn't until Buck got bitten on his right-hip by Little Das' mother that either were easy to identify.
The duo were first seen playing a game called "walk away from the herd and let everyone know about it". They then decide to forage nearby. While they do Little Das sneaks up on them and upon noticing the two bolt, and they run right into Das' sisters while Das chases them from the sides. They then corral them into their trap, their mother. Blaze became frozen from fear, but Buck was able to get her to run, but in doing so fails to save himself and Das' mom bites him on his right-thigh. Ironically, Das, in his eagerness gets distracted by Blaze and accidentally rams his mom and makes her let go, and Buck takes the opportunity to escape. Even so, Buck still received a major scar, causing him to adopt a limping gait. Buck's injury was serious: Das' mother has bitten quite far in his flesh, and the Daspletosaurus know that eventually Buck will become so weak from it he won't be able to walk anymore and his herd will leave him for dead.
The next day while the tyrannosaurs prepare to finish what they started, Das was secretly abandoned while watching Buck. After he noticed he attacked a herd of Einiosaurus, while searching for his family, who came running to the Maiasaura which alerted them of the menace. They retreat with the ceratopsians and Buck gets to live again.
Sometime later, the two herds have become allies. Buck continues to limp: his wound getting worse, and Das and his family still pursue him. Once again the tyrannosaurs attack. Little Das first chases them towards his family. Blaze nearly runs into Das' mom and sisters again, but swerves away and they let her go, since they still want Buck who smartly took shelter between some Einiosaurus. The ceratopsians create a blockade to allow Buck to get away. Buck takes the kind offer and sneaks off to get back to his herd. However Little Das spots him and alerts his family and they continue after him. Buck no longer could run, but the tyrannosaurs simply decide to walk after him rather than simply rush in and finish him while they could. He tries to follow Blaze while she continues to move further away from him.
The ash cloud produced by the volcano blocks out the sun and starts raining volcanic-glass and soot making it very dark. Buck resorts to calling out to his herd and follows their voices. Then the ash begins to lift letting sunlight through revealing the herd to Buck. Buck gets to the herd but finally loses all strength in his limbs and collapses. Despite this Das and his family chose to gain back energy they lost from the trek before eating him. However, about a few hours later, the east side of the erupting volcano collapses creating a pyroclastic flow which heads towards them. After they notice the approaching flow, Little Das and his family decide to leave Buck for dead rather than finish him as the danger posed by the flow was too apparent to ignore. The rest of the Maiasaura also take notice of the oncoming flow a few seconds later and run, unconcerned about Buck (possibly including Blaze), while the terrified Buck desperately tries to get back up. Though this wouldn't matter as the pyroclastic-flow sweeps over the herd and kills them, Buck and Blaze included (their nemesis is killed shortly after).
- They are the first characters in the series to be herbivores.
- Buck is a lighter color of brown than the other male Maiasaura most likely because he's a juvenile.
- Buck is the second character to have a injury.